<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>39.es7新特性</title>
</head>
<body>
<script>
  let arr1 = ['a','c','d']
  //es5 之前使用的是indexof es6可以使用includes
  console.log(arr1.includes('a'))//true
  console.log(arr1.indexOf('a')) //0
  console.log(arr1.indexOf('99'))  //-1
  //幂运算 es5之前用的是Math.pow(2,10)
  console.log(2 ** 10)  //1024
  console.log(Math.pow(2,10)) //1024
</script>
</body>
</html>